grain

grain, in agriculture, term referring to the caryopsis, or dry fruit, of a cereal grass. The term is also applied to the seedlike fruits of buckwheat and of certain other plants and is used collectively for any plant that bears such fruits. The food content of the seeds (as they are commonly called) is mostly carbohydrate, but some protein, oil, and vitamins are also present. Grain, whole or ground into meal or flour, is the principal food of man and of domestic animals. The seeds of most grains grow in concentrated clusters that are gathered efficiently by modern mechanical harvesting machines (see combine). Grain is easy to handle and, because of its low water content, can be stockpiled and stored for long periods, unlike other starch foods (e.g., the potato). Grains, both living and stored, are attacked by a variety of insect pests (e.g., the corn borer, locust, and grasshopper) and by smuts, rusts, blights, rots, and other diseases of plants. The principal grain crops, in order of total world output, are wheat, rice, Indian corn (or maize), oats, barley, and rye; together, these grains occupy about half of all the land under crops. All the staple grains were domesticated in the Neolithic period, or New Stone Age, and their cultivation was a powerful factor in drawing men into settled communities. Many religious beliefs and rites have been associated with grains; the cereals derive their name from Ceres, the Roman goddess of grain. Grain has been an article of commerce in nearly all civilizations.